INFO: task kworker/u4:6:4787 blocked for more than 120 seconds.
      Not tainted 4.9.108-gb7d377b #47
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:6    D25336  4787      2 0x00000000
Workqueue: netns cleanup_net
 ffff880183364800 0000000000000000 ffff8801cf439f80 ffffffff84629800
 ffff8801db221c18 ffff8801cec37770 ffffffff839e8aed ffffffff85597ad0
 ffff880183364800 00000000000058b1 00ff880183365158 ffff8801db2224e8
Call Trace:
 [<ffffffff839ea0ef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f6501>] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768
 [<ffffffff839ed2b3>] do_wait_for_common kernel/sched/completion.c:75 [inline]
 [<ffffffff839ed2b3>] __wait_for_common kernel/sched/completion.c:93 [inline]
 [<ffffffff839ed2b3>] wait_for_common kernel/sched/completion.c:101 [inline]
 [<ffffffff839ed2b3>] wait_for_completion+0x203/0x2e0 kernel/sched/completion.c:122
 [<ffffffff8119dd46>] kthread_stop+0xa6/0x5d0 kernel/kthread.c:513
 [<ffffffff830f828e>] pg_net_exit+0x3de/0x6e0 net/core/pktgen.c:3923
 [<ffffffff83059d50>] ops_exit_list.isra.6+0xb0/0x160 net/core/net_namespace.c:136
 [<ffffffff8305cc21>] cleanup_net+0x321/0x630 net/core/net_namespace.c:473
 [<ffffffff8118d121>] process_one_work+0x7e1/0x1500 kernel/workqueue.c:2092
 [<ffffffff8118df16>] worker_thread+0xd6/0x10a0 kernel/workqueue.c:2226
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f9b9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

Showing all locks held in the system:
1 lock held by kworker/dying/6:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by kworker/dying/18:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by kworker/dying/22:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by kworker/dying/252:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425cb7>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3679:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d803c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3776:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f7b92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211fce2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
3 locks held by kworker/u4:6/4787:
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d02e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d02e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  (net_cleanup_work){+.+.+.}, at: [<ffffffff8118d068>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
 #2:  (net_mutex){+.+.+.}, at: [<ffffffff8305ca3f>] cleanup_net+0x13f/0x630 net/core/net_namespace.c:439
1 lock held by kworker/dying/4826:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor2/10172:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by kworker/dying/13367:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by kworker/dying/20986:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor0/22903:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor7/28502:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by udevd/31870:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor4/2526:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/3849:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/3852:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/3853:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/3864:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/3869:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by getty/3872:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by kpktgend_0/4042:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by kpktgend_1/4053:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor2/4075:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor2/4081:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor2/4140:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor2/4142:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor2/4146:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor2/4147:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor7/4077:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor7/4086:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor7/4141:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor7/4145:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor0/4093:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor0/4098:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor0/4144:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor4/4102:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor4/4104:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor4/4148:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor4/4149:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328
1 lock held by syz-executor4/4150:
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] __blocking_notifier_call_chain kernel/notifier.c:316 [inline]
 #0:  ((task_exit_notifier).rwsem){.+.+..}, at: [<ffffffff811a2db8>] blocking_notifier_call_chain+0x68/0xa0 kernel/notifier.c:328

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.108-gb7d377b #47
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d9127d08 ffffffff81eb3e29 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b96a0 ffff8801d9127d40
 ffffffff81ebf127 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb3e29>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb3e29>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebf127>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebf0ba>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b97a4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366bc4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366bc4>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366bc4>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366bc4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f9b9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff839f85f6